Variable pitch propeller



March 17, 1970 A Q ETAL 3,501,251

VARIABLE PITCH PROPELLER Filed Jan. 24, 1968 4 Sheets-Sheet 1 FLUIDPRESSURE SOURCE AND CONTROLS INVENTORS. KJELL HAGLUND 8| OLOF JOHANGERHARD HEDBERG their ATTORNEYS March 17, 1970 c-; ETAL 3,501,251

VARIABLE PITCH PROPELLER Filed Jan. 24, 1968 v 4 Sheets-Sheet 2 flyi INVENTORS.

KJELL HAGLUND 8| OLOF JOHAN GERHARD HEDBERG JZL M f their ATTORNEYSMarch 17, 1970 K. HAGLUND ETA!- 3,501,251

I VARIABLE PITCH PROPELLER Filed Jan. 24, 1968 v 4 Sheets-Sheet 5 h(will INVENTORS. KJELL HAGLUND 8u OLOF JOHAN GERHARD HEDBERG W%, f gQAL.

their ATTORNEYS March 17, 1970 I HAGLUND ETAL I 3,501,251

VARIABLE PITCH PROPELLER Filed Jan. 24, 1968 4 Sheets-Sheet 4 INVENTORS.KJELL HAGLUND 8| OLOF JOHAN GERHARD HEDBERG eir ATTORNEYS United StatesPatent 3,501,251 VARIABLE PITCH PROPELLER Kjell Haglund and Olof JohanGerhard Hedberg, Karlstad, Sweden, assignors to Aktiebolaget KarlstadsMekaniska Werkstad, Karlstad, Sweden, a company of Sweden Filed Jan. 24,1968, Ser. No. 700,151 Claims priority, application Sweden, Mar. 22,1967, 3,987/67 Int. Cl. B63h 1/06, 3/00 US. Cl. 416--157 6 ClaimsABSTRACT OF THE DISCLOSURE BACKGROUND OF THE INVENTION This inventionrelates to variable pitch propellers such as those employed in ships,turbines, pumps and the like.

Variable pitch propellers of various types have been proposed and usedin the past in ships, turbines, pumps and other types of bladed devices.In the usual variable pitch propeller, the propeller blades arerotatably mounted on a hub and are coupled to a blade pitch controlmechanism which selectively pivots the blades about their mounting axesto vary their pitch and set them at a desired pitch. A number of formsof pitch control mechanisms employing mechanical, electro-mechanical andhydraulic principles have been suggested.

Many known hub designs, especially in the case of large diameterpropellers, present diflicult design problems on account of the weightand axial length of the hub. In ship propellers, for example, it isoften of considerable importance to keep the length of the hub as smallas possible, having regard for the clearance in the propeller aperture,and to keep the weight of the hub as low as possible, having regard forthe bearing loads and the bending stresses in the propeller shaft. Anexcessive length and weight of the hub also has an unfavorable effectupon the operating characteristics of certain kinds of turbines.

Some previously proposed pitch control mechanisms have one or morehydraulic pistons which are coupled by axial piston rods to powertransmitting devices which transmit the piston movement to the propellerblades. These piston rods impart pivotal movement to the blades by meansof sliding blocks or links. Some types require hubs which are extremelyheavy in relation to the total propeller weight and are excessively longin relation to the axial space which is required for the fitting andpivoting of the blades in the hub. To be reliable in service, theyrequire precision manufacture and large, strong parts, partly forguiding and sealing the pistons in the cylinders and partly for theguiding of devices which transmit power to the blades.

SUMMARY OF THE INVENTION The purpose of this invention is to provide apropeller hub structure embodied in a pitch control mechanism which isfree of many of the disadvantages found in 3,501,251 Patented Mar. 17,1970 "Ice existing propellers, and particularly to provide a hubstructure which is light in weight, compact in size, strong and durable,essentially trouble-free, and of low cost as to construction, maintanceand repair.

More particularly, a propeller, according to the invention, includes afluid-operated pitch control mechanism, preferably a hydraulic-operatedmechanism, located in the hub. The mechanism comprises a double pistonstruc ture in the form of a rigid unitary member composed of two pistonelements which are axially movable in two separate opposed fluidcylinder units, one of which is positioned on each side of the doublepiston structure in the axial direction of movement of the same, the twocylinders being fixed in the propeller hub. The cylinder units and thepiston elements form two fluid-pressure chambers for actuating thedouble piston structure, and power transmitting elements couple thedouble piston structure to the propeller blades such that axial motionof the piston structure imparts rotary motion to the blades to varytheir pitch.

Each of their piston members, i.e., the members constituting movingwalls or parts of the fluid chambers, making up the double pistonstructure may have either an internal or an exterior cylindrical surfacearranged to slide along a mating cylindrical surface of the companioncylinder unit. The cylinder units, i.e., those parts that constitutefixed walls of the fluid chambers, similarly, of course, may have eitherinternal or external cylindrical surfaces along which the companionpiston member slides. Preferably, the cylindrical guiding and sealingsurfaces of the pistons and cylinders are coaxial and of equaldiameters.

DESCRIPTION OF THE DRAWINGS For a better understanding of the invention,reference may be made to the following description of exemplaryembodiments, taken in conjunction with the accompanying drawings, inwhich:

FIG. 1 is a side view in section, taken generally along an axial plane,of one embodiment of the invention;

FIG. 2 is an end view in section through the embodiment of FIG. 1, thesection being taken generally along the plane represented by the linesAA and in the direction of the arrows;

FIG. 3 is a side view in section taken along a generally axial plane ofanother embodiment of the invention, the view being in generallyschematic form;

FIG. 4 is a generally schematic view in section taken along an axialplane of a third embodiment according to the invention;

FIG. 5 is a generally schematic, side sectional view taken along anaxial plane of a fourth embodiment; and

FIG. 6 is a generally schematic, side view in axial section of anotherembodiment of the invention.

DESCRIPTION OF EXEMPLARY EMBODIMENTS The embodiment illustrated in FIGS.1 and 2 includes a hub body 1 which is constructed to carry fourpropeller blades 3'. Within the body is an axially disposed cavity orbore which receives, inter alia, a hydraulic pitch-control mechanism(described below), [The hub body 1 has four peripherally spaced recesses7 for pivotal mounting of the propeller blades 3. (Only the bladeflanges 9 and the innermost root portions of the blades are shown on thedrawings.) Each propeller blade 3 is rotatably attached for pitchvariation to the hub body 1 by means of a mounting structure composed ofbearing ring 11 which is fastened, such as by threads, to the hub body 1and a crank pin ring 13 which is attached to the blade flange 9 andprovided with a crank pin 15 (FIG. 2). The crank pin ring 13 is pivotedon a journal bearing 17 positioned in the hub body recess 7.

The hub body 1 is fastened to a flange 19 on a propeller shaft drive 21,and the propeller shaft 21 has a central, axial bore 23. Extendingthrough the bore 23 is a pipe 25 which is arranged for movement in theaxial direction through the shaft bore. The pipe 25 and the annulus inthe bore 23 between the pipe 25 and the walls of the bore both serve assupply and return conduits for a hydraulic fluid to the hydraulicmechanism in the hub 1. At the opposite end of the hub body from thepropeller shaft flange 19 are an end cover 27 and a hub cone 29, thecone and cover being sealed to the body.

The hydraulic mechanism provides for the transmission of power from thepressure fluid to each propeller blade 3 through the crank pins 15 onthe crank pin rings 13 and includes a one-piece double piston structure31 located in the cavity or bore 5 of the hub body. The double pistonstructure 31 consists of two piston portions including on one side aportion 33 which in the form shown in FIGS. 1 and 2 has an externalcylindrical guiding and sealing surface 35 which seals against aninternal cylindrical face 37 on the end cover 27, these elements beingsealed by a seal ring 39 and thereby defining a closed fluid chamber 41for the pressure fluid. On the other end of the piston structure 31 is apiston portion 43 which seals against an external guiding and sealingsurface 47 of a cylinder unit 49, which is affixed to the hub body 1,thereby defining a chamber 51 for pressure fluid actuating the pistonportion 43.

The cylinder unit 49 has an opening 53 in its end wall which is sealedby a seal 55 to and receives a tube section 57. The tube section 57 isjoined at one end to the piston structure 31 and is provided with anaxial bore 59 having a Wider section 61 at the shaft end and a narrowersection 63 at the piston end. The pipe 25 extends through the widersection 61 of the bore 59 and is coupled at the end of this section tothe narrower section 63, thus connecting it to the fluid chamber 41 forsupply and return of pressure fluid to and from the chamber 41. Theannular space in the bore 23 between the pipe 25 and the wall of thebore communicates with the Wider section 61 of the bore 59 and thencethrough radial holes 65 to the fluid chamber 51 for supply and return ofpressure fluid to the chamber 51. The supply and return of pressurefluid to and from the chambers 41 and 51 are controlled by a suitablevalve control unit which will generally be remote from the propeller huband located at a control point. Any appropriate source of fluidpressure, and preferably hydraulic pressure, can be employed.

In one form of known control system for variable pitch propellers, theflow of hydraulic fluid to and from the hydraulic mechanism in the hubis regulated by means of a pilot valve located in the hub. Such a pilotvalve is operated by axial movement of a pipe corresponding to pipe 25in FIG. 1. Other than for this purpose the pipe 25 usually serves onlyas a supply pipe for pressure fluid while the annulus between the pipeand the shaft bore wall serves as a return conduit. An arrangement of apilot valve in the hub is shown in Swedish Patent No. 93,872 and canwith advantage be used in a propeller according to the presentinvention.

Referring particularly to FIG. 2, the double piston structure 31 isprovided with lugs 67, one for each propeller blade 3, which extend outgenerally radially from the piston structure 31 through openings 69 inthe hub body 1. These openings 69 allow the lugs 67 to move in an axialdirection within the hub body 1 a distance necessary for any desiredrotational movement of the propeller blades 3. The lugs 67 arepreferably located on the central part of the double piston 31. In theform shown, each lug 67 is coupled to a propeller crank pin 15 by meansof a sliding block 71 in which the crank pin 15 is rotatably pivoted.The sliding blocks 71 are arranged to slide in bearing grooves 73machined in the lugs 67 with guide surfaces perpendicular to thelongitudinal axis of the piston structure 31.

It is desirable in the propeller pitch control mechanism according tothe invention to construct the unit such that one of the pistonportions, e.g., 33, has an external guiding and sealing surface 35sliding within a fixed inner seal 39 on its cylinder unit 37 while theother piston unit 43 has an inner seal 45 sliding along an externalguiding and sealing surface 47 of its cylinder unit 49. With thisconstruction, the possibility of the piston structure sticking as aresult of asymmetrical load from the propeller blades 3 is considerablyreduced. A particularly short hub length is possible if, as shown inFIGS. 4 and 5, one of the cylinder units is recessed in the propellershaft 21. It is also desirable that the guiding and sealing surfacesbetween the two piston portions and the respective cylinder units becoaxial and of equal diameters. This construction provides operation ofthe device without any pumping effect in the cavity 5 as the pistonstructure is moved back and forth.

Because the double piston structure 31 is guided along two stationarycylinder units (37 and 49), only two cylindrical guiding and sealingsurfaces (35 and 47) need to be accurately machined over their entireaxial length while the opposite cylindrical surfaces only need to bemachined in the areas adjacent to their seals (39 and 45). Fabricationof the unit is thus simplified, and the costs are correspondinglyreduced.

FIGS. 3 to 6 show, in generally schematic form, various alternativeconstructions embodying different arrangements in the guiding andsealing of the piston portions 33 and 43 of the double piston structure31 along the two cylinder units in the hub body 1. The referencenumerals for each figure are the same as those applied to the embodimentof FIGS. 1 and 2, but with the addition of a letter suflix for eachalternative embodiment. Inasmuch as the structure and operation of theembodiments of FIGS. 3 to 6 are basically the same as those of theembodiment of FIGS. 1 and 2, elaborate description of FIGS. 3 to 6 isunnecessary, and reference can be made back to the foregoingdescription, taken in conjunction with the points mentioned below.

The embodiment of FIG. 3 shows an arrangement correspondingsubstantially to that in FIG. 1. The piston portion 33a of the doublepiston structure 31a remote from the propeller shaft 21 is provided withan external guiding and sealing surface 35a arranged to slide along aninternal seal 3911 on the fixed cylinder unit 37a. The piston portionunit 430 adjacent to the propeller shaft 21 is tubular and provided withan internal seal 45a arranged to slide along the external guiding andsealing surface 47a of the cylinder unit 49a.

FIG. 4 shows an arrangement in which the piston portion 33b is tubularand provided with an internal seal 77b which is arranged to slide alongthe external guiding and sealing surface 79b of the cylinder unit 81b.The piston piston portion 43b is provided with an external guiding andsealing surface 83b arranged to traverse an internal seal 85b on thecylinder unit 87b.

In the embodiment of FIG. 5, the piston unit 330 is provided with anexternal guiding and sealing surface 35c which is arranged to traversethe internal seal 390 of the cylinder unit 37c. The piston portion 43bis similarly provided with an external guiding and sealing surface 83carranged to traverse the internal seal 85c on the cylinder unit 870.

According to FIG. 6 the piston portion 33d is tubular and has aninternal seal 77d which is arranged to slide along an external guidingand sealing surface 79d of the cylinder unit 81a. The piston portion 43ais also tubular and provided with an internal seal 45d arranged to slidealong the external guiding and sealing surface 47d of the cylinder unit49d.

The above-described embodiments of the invention are intended to bemerely exemplary, and those skilled in the art will be able to makenumerous variations and modifications of them without departing from thespirit and scope of the invention.

We claim:

1. In a variable pitch propeller for use in ships, pumps, turbines andthe like which includes a hub carrying a plurality of propeller blades,each blade being mounted for rotation about an axis generally radiallyof the hub for adjustment of its pitch, the combination therewith of amechanism for rotating the blades to adjust their pitch comprising aunitary double piston structure carried in the hub and including acommon wall portion transverse to the hub axis and first and secondskirt portions mounted on the common wall portion and disposed axiallyon the hub, the first skirt portion having an external cylindricalsurface and the second skirt portion having an internal cylindricalsurface; means defining a first cavity in the hub including a memberfixed on the rub and having an internal cylindrical surface slidablymating with the cylindrical external surface of the first piston skirtportion thereby to define a first fluid chamber on one side of thepiston common wall portion; means defining -a second cavity in the hubincluding a member fixed on the hub and having an external cylindricalsurface slidably mating with the cylindrical internal surface of thesecond piston skirt portion thereby to define a second fluid chamber onthe other side of piston common wall portion; the said cavities beinglocated in opposed relation and said second skirt portion having aportion of its outer wall formation located in proximity to theintersections with such skirt portion of the said pivot axes of thepropeller blades; a crank linkage between the piston and each of thepropeller blades located in proximity to the said intersections andincluding elements associated with the said proximate portion of thesecond skirt portion of the piston structure for coaction with anelement on each blade; and means for selectively communicating one orthe other of the fluid chambers with a source of fluid pressure, thepiston being shifted in one direction axially of the hub in response toapplication of fluid pressure in one of the chambers and being shiftedin the opposite direction axially of the hub in response to applicationof fluid pressure in the other of the chambers, thereby to change thepitch of the blades.

2. The combination according to claim 1 wherein the crank linkageincludes a lug on the said proximate portion of the piston second skirtportion inwardly of each blade and having a crank pin slot formedtherein, a crank pin on each blade extending into the respective crankpin slot, and bearing means interposed between each crank pin and crankpin slot. 7

3. The combination according to claim 1 wherein the piston first sleeveportion extends in one direction from the wall portion, and the secondsleeve portion extends in the other direction from the wall portion.

4. The combination according to claim 3 wherein the first sleeve portionextends rearwardly from the wall portion relative to the shaft carryingthe propeller and the second sleeve portion extends forwardly from thewall portion.

5. The combination according to claim 1 further comprising a propellerdrive shaft coupled to the hub and including a bore therethrough, aconduit extending through the bore in the shaft and movable axially ofthe shaft and coupled to the piston structure for movement therewith,the outer surface of the conduit being spaced from the wall of the boreto define a passage, means associated with the piston structurecommunicating the interior of the pipe with one of the fluid chambersand communicating the passage With the other fluid chamber.

6. The combination according to claim 1 wherein the cylindrical surfacesof the respective piston portions and cavities are coaxial and ofsubstantially equal diameters.

References Cited UNITED STATES PATENTS 3,150,570 9/1964 Johnson et al 92172 X 3,163,231 12/1964 Barnes et a1. 160.32 X 3,212,586 10/1965 Barneset al. 170-16032 X FOREIGN PATENTS 789,794 8/1935 France. 1,083,482 6/1954 France. 1,256,667 2/ 1961 France.

EVERETTE A. POWELL, JR., Primary Examiner 53 3 UNITED STATES PATENTOFFICE CERTIFICATE OF CORRECTION Patent 150L951 Dated March 17, 1970InventOr( K. HAGLUND ET AL.

It is certified that error appears in the above-identified patent andthat said Letters Patent are hereby corrected as shown below:

Column 2, line 4, "maintance" should be --maintenance-; line 21, "their"should be the-; line 24, "exterior" should be -external-.

Column 5, line 17, "rub" should be hub-.

Column 6, line 28, after "piston" insert --skirt--.

SIGNED AN'U SEALED JuL211970 ISEAL) Atteat:

Edward M. Fletcher, Ir. WILLI m mu Anew-mg Officer Commissioner ofPatent;

